When manufacturing a structure by assembling a pair of members, the task of accurately positioning one of the members and the other of the members becomes necessary. As a method of such positioning, a method using a so-called plumb which has a weight hung at one end of a thread has been used conventionally. To use such a plumb, first, positioning holes are formed respectively at the places at which the positions of both members are to be aligned. Next, each of the members is separately disposed upward and downward, and the thread of plumb is passed through a hole of the one of the members located above to hang the weight vertically downward. While maintaining the weight so as to match the position of the hole of the other of the members located downward, the one of the members is descended toward the other of the members, or the other of the members is ascended toward the one of the members. Then, by matching the hole of the one of the members with the hole of the other of the members, the pair of members can be accurately positioned.
The positioning using the plumb is used as an effective positioning device especially when the surface of each member is a curved surface. This is because when the positioning holes are formed in each of the members orthogonal to the curved surface, the directions of axes of the holes do not coincide with the one of the members and the other of the members located vertically below it, making it impossible to see the hole of the other of the members through the hole of the one of the members.
As an example of the structure, an aircraft structure such as a main wing of an aircraft can be taken.
The present applicant has conventionally propounded an aircraft apparatus for manufacturing a structure whereby it is possible to ascend or descend one of the members toward the other of the members with high accuracy (see Patent Document 1).